关键词：
成熟温度;牦牛乳硬质干酪;蛋白质降解;苦味
摘 要：
为了了解提高成熟温度对牦牛乳硬质干酪成熟过程中蛋白质降解与苦味程度的影响,本文研究了5、10、15℃成熟牦牛乳硬质干酪在1~6个月成熟过程中p H值4.6可溶性氮含量、12%TCA可溶性氮含量、5%PTA可溶性氮含量、游离氨基酸和苦味程度的变化,并利用RP-HPLC对p H值4.6可溶性氮提取物肽分布进行了分析。结果表明:成熟温度和时间显著影响干酪成熟过程中以p H值4.6可溶性氮含量、12%TCA可溶性氮含量、5%PTA可溶性氮含量、游离氨基酸等所体现的蛋白质降解程度。提高成熟温度导致p H值4.6可溶性氮含量、12%TCA可溶性氮含量、5%PTA可溶性氮含量、游离氨基酸含量等增加,特别是15℃在成熟早期能较快增加干酪12%TCA可溶性氮含量、5%PTA可溶性氮含量。RP-HPLC分析显示从5℃提高到15℃时,干酪p H值4.6可溶性氮提取物亲水性肽含量增加,疏水性肽含量降低。除5、10、15℃成熟2个月干酪具有非常轻微的苦味之外,15℃成熟干酪比5、10℃成熟干酪具有较强苦感,成熟4个月后,10、15℃成熟干酪具有中等较强苦味,且差异不显著(P≥0.05)。该研究为加快牦牛乳硬质干酪成熟提供了试验数据。
译 名：
Influence of Elevated Ripening Temperature on the Proteolysis of Hard Cheese From Yak Milk
作 者：
SONG Xuemei;LIANG Qi;ZHANG Weibing;ZHANG Yan;BAO Zhenrong;College of Food Science and Engineering,Gansu Agricultural University;laboratory of Functional Dairy;
关键词：
ripening temperature,hard cheese from yak milk,proteolysis,bitterness
摘 要：
In order to investigate the effects of ripening temperature on proteolysis and bitterness in hard cheese made of Yak milk cheese,cheeses ripened at 5. 10 and 15℃ at 1,2,3,4,5 and 6 months were aralyzed to determine proteolysis through the level of soluble nitrogen at p H 4. 6,in 12% trichloroacetic acid and 5% phosphotungstic acid,total free amino acid content and RP-HPLC analysis of the water-soluble fraction at p H 4. 6. Proteolysis was significantly affected by ripening temperature and time. Elevated temperature could drastically increase the level of soluble nitrogen at p H4. 6,in 12% trichloroacetic acid and 5% phosphotungstic acid and the content of total free amino acids,especially ripening temperature at 15℃ could raise substantially soluble nitrogen in 12% trichloroacetic acid and in 5%phosphotungstic acid during the early months of ripening. RP-HPLC analysis showed that with the ripening temperature elevation,hydrophilic peptide levels in the p H4. 6 soluble fractions increased and hydrophobic peptides levels decreased. Bitterness of cheese ripened at 5,10 and 15℃ for 2 months was distinct,but at low level. Cheese ripened at15℃ had more bitter than Cheese ripened at 5℃ and 10℃. Cheese ripened at 10℃ and 15℃ from 4 to 6 months had moderately strong bitterness and difference was not significant( P ≥0. 05). The study provides experimental datas for auelerating the ripening of hard cheese from yak milk.
